Automotive drum-type brakes generally incorporate a brake shoe which is pivotally mounted to the backing plate by an assembly which is commonly referred to as the hold-down assembly. There are several designs for the hold-down assembly which are presently in use. One design of this type assembly consists of a pin, a helical compression spring and a retainer nut which is in the shape of a round cup. Other designs incorporate the same type pin which is used with the retainer nut however, the retainer in such other designs generally incorporates a U-shaped flat spring type retainer. In the prior art, the pins utilized to hold the brake shoe to the backing plate are referred to as tension pins and these pins and the various types of automotive brakes incorporating a brake shoe will differ in length only. In all cases, where the tension pin is used to hold the brake shoe pivotally to the backing plate, the tension pin is mounted to the backing plate by passing the pin through an opening in the backing plate and subsequently through an opening in the brake shoe after which a spring type retainer is utilized and the tension pin placed in tension by rotation of the retainer thereby locking the assembly together.
In the prior art various types of tools are utilized to perform the locking function when a retainer nut is used in conjunction with the tension pin. There is no tool presently available which can be used to lock the U-shaped flat spring retainer to the tension pin.
In the prior art, as the tension pin is pushed through the backing plate and subsequently through the brake shoe and the helical compression spring, the tools of the prior art required that the retainer nut be pushed against the helical compression spring and over the locking flanges of the tension pin. The retainer nut was thereafter rotated approximately 90 degrees and the bearing compression of the spring against the retainer relieved. The relief of the spring compression secured the mounting flanges of the pin against the retainer nut thereby holding the brake shoe to the backing plate to permit relative pivot rotation of the brake shoe with respect to the backing plate. To disassemble the brake shoe from the backing plate, the retainer cup was pushed by the prior art tool against the helical compression spring which relieved the compression of the tension pin flanges against the retainer nut. The retainer nut was thereafter rotated until the tension pin flanges were aligned with a slot in the retainer nut through which the tension pin flanges could pass as compression on the helical spring was relieved.
The prior art tools used to accomplish the engagement and disengagement of the retainer nut gripped and turned the retainer nut as the nut was in bearing compression against the helical spring. In some instances, a pair of pliers with jaws especially shaped to be able to grip the retainer nut were utilized. In many instances however, while using the prior art tools, it was difficult to disengage the retainer nut from the pin and the use of such tools prevented the user from utilizing other tools in an attempt to loosen the nut from the pin. Where the U-shaped flat spring retainer-type nut was employed, there were no especially designed tools which could be used to lock the tension pin and U-shaped retainer together; this was achieved through the resourcefulness of the mechanic who was required to adapt existing tools to accomplish that purpose. In addition to the limitations in the use of the prior art tools, the production costs of manufacturing the prior art tools were excessive because the tool incorporated separate parts which required separate manufacture and thereby added to the higher cost of production.